Many years ago, when we live in a particular house in Belfast, we had a postbox right outside our house. Well, actually, it was the other side of the Antrim road, but the point is that it was very, very handy. If you wanted to post something, you just stuck a stamp on it and ran across the road and stuck it in the postbox.
Here in the states they have an even better system for sending out outgoing post. If you want to post something, you stick it in your mailbox, and you stick up a little red flag. Then when the "mail carrier" comes along to leave in your post, she takes away the outgoing post.
Isn't that fantastic?
There are other little differences between the UK and the USA when it comes to post. It's traditional here to write the sender's address in the top left of envelopes here. I think I read somewhere that that's because the post office won't open mail if they want to return it to sender - if the sender's address isn't on the outside, and they can't deliver it, I guess they just throw it out. In the UK, they open it up to try and figure out who to send it back to. (At least, I think they do.)